Photocurrent multiplication of a-Si : H/a-SiC : H staircase photodiodes with sawtooth graded-gap multiplication region was observed for the first time. Multiplication factors M of about 6 were confirmed in 3×1000Å (500Å : a-Si : H, 500Å a-Si_<1-x>C_x : H) sawtooth multiplication region. This value is 3 time bigger than that of the usual a-Si : H pin photodiode. It was found that the photocurrent multiplication factor was changed by the band offset of the sawtooth band structure.
